1. Field of the Invention
The present invention relates to a hand-held ocular fundus imaging apparatus, and specifically to a hand-held ocular fundus imaging apparatus wherein an examiner takes hold of a grip by hand and secures a face pad or the hand holding the grip against part of a patient's face to form an fundus image of the patient's eye.
2. Description of the Prior Art
In conventional practice, there have been small hand-held fundus cameras wherein an examiner takes hold of a grip by hand and secures the apparatus against part of a patient's face to photograph the fundus (Japanese Laid-open Patent Application Nos. 2005-143805 and 1992-256726).
Examples of known fundus cameras include a fundus camera wherein illuminating light is directed onto the fundus via a reflecting mirror disposed in the optical path of a photographic aperture and a cornea, and alignment is performed by varying the angle of the reflecting mirror (Japanese Laid-open Patent Application No. 2002-345758). A fundus camera is also known in which alignment is performed by moving slit light with the aid of a mirror in two dimensions to illuminate the fundus (Japanese Laid-open Patent Application Nos. 1994-7301 and 1981-83326).
The conventional hand-held fundus cameras have problems in that since the positional relationship with the patient's eye is not stable, it is difficult to align the photographic optical system with the patient's eye, i.e., to perform an alignment operation. In order to reduce the size of the fundus camera to make it light in weight, the working distance becomes as short as 10 mm or less. Since the main body is still heavy and alignment is difficult, it is not easy to operate the apparatus comfortably, and since the working distance is short, the distal end of the fundus camera is highly likely to come into contact with the cornea of the patient's eye, thus creating constant danger.
The present invention was devised in order to resolve such problems, and an object thereof is to provide a hand-held ocular fundus imaging apparatus that is lightweight and compact and is capable of performing alignment easily while ensuring a working distance.